DENVER — For a new band touring behind its first record, Audioslave are off to a pretty good start. Following a slate of European dates, the offspring of Rage Against the Machine and Soundgarden kicked off their first tour of North America at the Fillmore Auditorium on Friday night, unleashing a slow-grinding set to a sold-out crowd of 3,600.

If lead singer Chris Cornell felt any nerves about hitting the road with Audioslave — the four-piece that pairs the former 'Garden godhead with Rage guitarist Tom Morello, bassist Tim Commerford and drummer Brad Wilk — it wasn't evident in his performance. Sporting a white tank top, toned and tattooed biceps and painted-on jeans, Cornell resumed his rock-star role with swagger and plenty of sex. Posing, preening and, occasionally, cracking a Cheshirian grin, Cornell led Morello and company through a 90- minute set that opened with "Light My Way," from Audioslave's eponymous debut LP, released in November.

But whether opening-night jitters or Denver's oxygen-deprived, mile-high altitude were to blame, Cornell at times struggled to find the notes. Moving from a screeching soprano to a deep, lusty croon, he hit a couple a clunkers along the way. Not that the capacity crowd cared: Introducing "his new friends," Cornell made his way around the stage to name-check his famous bandmates before testosterone-laden fans. Morello, the axeman behind Rage Against the Machine's bombastic hip-hop and metal-inflected sound, drew huge applause from an audience awash in vintage RATM T-shirts.

Standing tall on a guitar monitor in the middle of the stage, Cornell at one point asked the technical crew to raise the house lights: "This place looks bigger with the lights on," he said, surveying the packed room and a few impromptu mosh pits. "Oh, man, this is a whole crowd full of motherf---ers." Judging by the response, Cornell's comment was taken as a compliment.

Fans in the sea of sweaty bodies screamed as the band ripped through "What You Are," "Like a Stone" and "Gasoline." Making a joke at his own expense, the abstaining Cornell took a deep pull on a water bottle and said, "This is about all I can drink anymore." When a young guy in the crowd held up a beer and heckled, Cornell shot back: "Yeah, well, tell me about it in a few years, tough guy."

Following a brief break that brought much foot stomping and even a couple of fistfights in the front rows, Cornell returned to the stage strapped with an acoustic guitar; strumming the first chords of "I Am the Highway," a song he dedicated to the victims and families affected by the night club tragedy in Rhode Island the previous evening (see "At Least 96 Dead At Rock Show Fire" ). (Earlier in the night, Cornell had reminded the shoulder-to-shoulder throng to be aware of its environment — and the nearest exits.) Morello, Wilk and Commerford resumed their spots behind Cornell to finish the tune before launching into a raucous "Cochise," which nearly sent fans over the edge: Lighters flickered in the air as the band offered a curt "Good night" and walked off stage.

Audioslave can be forgiven for offering a rather brief set. At roughly a year old, the band doesn't have a lot of material to work with. Friday's performance was enough to quiet critics who regard the group as more of a marketing gimmick than a meeting of like-minded musical talents. Though elements of both Soundgarden and Rage run through the band's material — which moves from minor-chord and low-groove melodicism to more frenetic and bombastic metal — the band is still forging its own unique identity and fine-tuning its live show. Audioslave came off as a new band with promise that's not yet as seasoned or polished as its members' past outfits — which is exactly what it is. It's a whole new animal, er, machine, with plenty of time to work out the kinks of its road show.